Amtrak: Charlotte to Atlanta

 I turned my Train Performance Calculator to passenger trains.  The Crescent.  A way-too-slow, runs where the people are when they are sleeping, train. 5:40 minutes for 260 miles from Charlotte to Atlanta.  Very not useful. How can it be fixed?  Let's take a look...

The route is chocked full of curves.  54 miles of the 257 mile route are 2 degree or sharper.  About half of that is 3 degrees or sharper.  It seems that 3 degrees was likely the design standard for the route.  NS has maintained 5 inches of superelevation in most places to keep the track speed up to 60 mph or higher as much as possible. 

Miles of curves between Charlotte and Atlanta by curvature (degrees)

There are so many curves, so closely spaced, it's rather impractical to speed up much between them and gain much reduction in running time.  In fact, the timetable actually limits the majority of the route to 60 mph, the max for 3 degree curves with 3 inches of underbalance.  Amtrak equipment is generally allowed 3" of underbalance in curves - slight centripetal force greater than the superelvation.

Boosting the horsepower through additional locomotives or electrification improves running time only a couple of minutes.

What does help is being able to run through those three degree curves faster.  Let's try a tilt train.

Talgo equipment has been tested to 8 inches of underbalance.  Other countries run tilt equipment from 7-9 inches.  So, I chose 8 inches. For reference, 

Increasing the under balance to 8" allows 80 mph on three degree curves with 5" of superelevation knocks over an hour off the running time.

Increasing track speed to 90 mph helps running time a bit, but involves nearly constant acceleration and braking.  Not very practical.  What would make 90 mph practical would be easing all curves over 2.2 degrees.  Added with tilt equipment, another 20 minutes could be saved.

Here's a summary of scenarios.

Some detail from the scenarios:

This is just a piece of the route, but it is very typical.  This is "as constructed" in the 19th century when the south didn't have the wealth to build to higher standard and there was no money subsequently to modernize.  

The sheer number and spacing of the three degree curves make running much faster than 60 mph an impracticality.  If you use tilt equipment and allow 8" underbalance, you can get to 80 mph without too much trouble.  But if you want more than that, you get into easing curves.  There are more than 50 miles of curves that would need attention. That's a very expensive proposition and not one a handful of Amtrak trains could justify.  

Conclusion?  Tilt equipment.  Getting the running time from Atlanta to Charlotte down under 4 hours makes a New York to Atlanta day train possible.  If similar improvements can be made along the North Carolina RR the the Durham to Petersburg HrSR route created, multiple NY to Atlanta trains become practical.  

For freight?  Electrification.  It's the roller coaster grades of this route that kill the average speed.  Electrification brings much higher HP and the potential for much higher average speeds.  See previous blog post.

Ultimately, this route's engineering is just so bad, it might only be suitable for freight and a separate HSR rail route might be needed for passenger.  The state of GA wasted some big money on a study of alternatives about a decade ago (https://www.dot.ga.gov/GDOT/pages/AtlantaCharlotteRail.aspx.)  

However, we'll never see any HSR construction if we can't show conventional passenger trains are attractive and the current schedules are not competitive.

Tilt trains are the practical answer.